My current school uses Judo belts (Yellow,Orange,Green,Blue,Purple,Brown,Brown-1,Brown-2,Brown-3,Black), the "traditional" curriculum is ridiculously structured, its basically a textbook of 3-6 month modules (3 for lower grades, 6 for higher) and you're expected to do your whole however many pages of techniques/drills then the requisite number of forms (I know, fucking forms) then spar a number of opponents equal to your level.

I'm kind of indifferent to belts really, I grade because its expected, and it wouldn't be a hell of a lot of fun to be in a class full of Brown belts who all started when I did while I'm only wearing yellow or whatever (not that we ever wear our belts), though I will freely admit that the idea of finally getting a black belt after dabbling in so many different styles would be nice.

That said, I chose the gym I train at because of its fight record and I train to be a better fighter, not for belts.

(Also please don't think we spend all our time doing curriculum stuff, its competition season so most classes are warmup, bagging, sparring).

I like belts. I like grading, next grading would be for shodan and 20 rounds of kumite. Belts are useful for tournament/training divisions. Higher belts get a freer reign on training choice and can usually do sparring while juniors stick to kihon or bag work.

I have never thought of why someone is ranked higher if I could kick their ass. I am pretty sure I can kick my sensei or shihan's ass but what does that prove?

It's good to have a goal and to have to perform under pressure.
I've got my brown belt promotion coming up next month and been training hard over the last few months. It's going to be approx 2hours of techniques, kata, press-ups, etc followed by 12 rounds of Kumite against fresh fighters.

Piss Poor Preparation = Piss Poor Performance

On the whole, my Rank isn't important to me. The people I have the pleasure to train with and learn from are far more important me. Just after Christmas I went and trained with our Judo friends on the other side of town and had no issue donning my white belt in my krotty gi and getting down to business.

Training and being healthy enough to train are what's important to me.
Gaining the belts and sharing the glory with other peeps who 'suffered' with me is the best feeling.

Back in TKD my only motivation to get the next belt was that I'd then learn new stuff (forms, kicks, etc.).

Subsequently I've been involved with things where you learn what the instructor is teaching that day, you don't see people doing something you're not allowed to do yet, just something you haven't learned (or usually for me something I've forgotten)...belt motivation dropped off the scale.